The area of a regular pentagon looks about twice as a big as the pentangle star drawn within it. Is it?
A circular plate rolls in contact with the sides of a rectangular tray. How much of its circumference comes into contact with the sides of the tray when it rolls around one circuit?
Four jewellers share their stock. Can you work out the relative values of their gems?
|Find the area of the shaded region in terms of $a$ and $b$?|